Facsimiles may receive unnecessary data such as advertisements, because then are connected to a PSTN and thus anybody can transmit fax data to the facsimiles if they know the fax numbers of the facsimiles. Additionally, although the importance of information in a modern society increases, the security of data that are transmitted and received via facsimiles is weak. Accordingly, there remains a demand for a technique capable of reinforcing the security of fax data by filtering a calling number and/or a destination number during transception of data via facsimiles and by allowing fax data to undergo an authentication procedure while the fax data is being transmitted.
Moreover, although the use and importance of an existing PSTN decrease due to developments in Internet technology and mobile communications, the usability of facsimiles is still very high. In particular, facsimiles serve as a very important office machine in offices. However, in a recent communications system where Internet or Intranet is well established and each personal computer is connected to the Internet or Intranet, inclusion of a facsimile by each person is inefficient in terms of costs and resource applications and does not satisfy fax data security suitable for this system and efficient facsimile use.
Therefore, a fax system is desperately required, which can satisfy the demands of a plurality of users connected to the Internet and an efficient combination of an Internet or Intranet network with a PSTN for fax data transmission that are connected to each other via a computer, and can provide various fax-data security functions and a fax data filtering apparatus.